Diamondback terrapins in Maryland: Research and conservation and Roosenburg 2010.pdfDiamondback terrapins (Malaclemys terrapin) appeal to humans because of their dark eyes, wide “smiling

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Beate Pfau & Willem m. RoosenBuRg

IntroductionDiamondback terrapins (Malaclemys

terrapin) appeal to humans because oftheir dark eyes, wide “smiling lips” andattractive,oftencontrastingblackandlightgreyskinpattern.

Theirvernacularnamederivesfromthesculpturedcarapace,whichoftenresemblescutdiamonds(Fig.2).Thecolorationisquitevariable, even within a local population.Figs. 3 and 4 illustrate two color patternvariants of the Northern Diamondbackterrapin(M. t. terrapin).

Diamondback terrapins owners easilyrecognizeindividualsbecauseoftheuniquecolorpatterns.Thesecolorpatternsremaindistinct in adults. However, as the turtlesgrowthepatternandcolorationchangesandthuscannotbeusedtorecognizeindividualsinpopulationstudies.Therefore,terrapinre-searchersmarkindividualsbyothermeans,e.g. passive integrative transponders (PITtags)and/ornotchingcertainmarginalscutes(Cagle,1939;seebelow).

Maleandfemaleterrapinsdifferintheirmaximum size. Males are smaller andcan attain a maximum carapace length of16cm,femalesgetmuchlargerandmayat-tainamaximumcarapacelengthof26cm.At10cmcarapacelengthandlarger,externalcha-ractersdistinguishmalesfromfemales.Maleshavelongerandthickertails(Fig.5).Olderfemales are much larger and have enlargedheadswithstrongjawsadaptedforcrushingtheirhard-shelledprey(seebelow).

Becausediamondbackterrapinsarecuteanddonotget too large, theyarepopularamong pet keepers. Unfortunately, they

are very sensitive to inferior housing,particularlytopoorwaterquality,andthe-refore they are recommended as pets foronly skilled keepers. SaChSSe was one ofthefirstEuropeanswhowasabletobreeddiamondback terrapins regularly (SaChSSe1984), and SzymanSki (2005) published adetailed report on keeping and breedingterrapins.

During the 19th and early 20th century,DiamondbackterrapinswereinhighdemandintheUnitedStatesasagourmetfood.By1900,therewereexperimentalbreedingfar-mstoevaluatethepotentialtosupplyfoodmarketwithdiamondbackterrapins(Coker 1906, Barney1922).However, the labourintensivenatureofraisingterrapins led toa collapse of the early terrapin farming.Currently, several diamondback terrapinbreeders in the US provide hatchlings forthe pet market. Hobbyists have boughtsome of the most attractively patternedterrapinsfromthecommercialmarketsandestablished breeding pairs in their homespresumably already in the early years ofthe20thcentury.

DemandfromterrapinfleshfromChinahaspromptedatleastonerenewedattemptatterrapinfarminginMaryland.Thisfarmerstill produces turtles and exports them toAsianfoodandpetmarkets(Pelton2006).Thefarmerdugseveralponds(1+hectare)in a corn field and stocked themwith ap-proximately 2,200 diamondback terrapins(among other species). He collects theireggsafterthefemalenestsandartificiallyincubates thousandsofhatchlings that areexported toChina.Thecolourfulonesare

Beate Pfau and Willem M. Roosenburg

Diamondback terrapins in Maryland: Research and conservation

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Diamondback terrapins in Maryland

Fig.1.WillWilliamSandMelanineheCkmanmeasuringahead-startedterrapin.Photo:B.Pfau.

soldinthepettradewhereindividualterra-pinscanbringasmuchas$150apieceandother are sent to turtle farms where theyarerearedforbreedingstockandfood.Itisdifficulttoimaginethatthisbusinesscanbe“profitable”and“self-sustaining”becauseofthewaterqualityrequirementsofterra-pins.Hopefully,regulatoryauthoritieswillmaintainkeenoversighttoensureahealthyenvironmentfortheterrapins.

Terrapinsarespecializedbrackishwaterturtlesandarefrequentlymentionedinsci-entificandpopulararticlesonUSestuarinehabitats. Despite their fame, popularity,andcharismaticnature; there ismuchthatremainstobelearnedaboutthissaltmarshdenison. Threatened by over-exploitation,nutrientloading,pollutionandhabitatloss,thediamondback terrapinshavebecomeasymbolfortheconservationeffortsforestu-arieswithintheUSA.Educationprogramsusetheactiveandfriendlyterrapinasafocal

speciesinconservationandeducationpro-gramstoeffectivelypromoteenvironmentalawarenessandstewardship.

The key to understanding terrapin con-servationandmanagement,aswithalmostallturtles,liesinlong-term,mark-recapturedata sets. One of us,Willem rooSenBurg conducts such long term research onMaryland’sdiamondbacksandhisfindingscontribute to sound terrapin conservation.Beate Pfau followed Willem during thesummerof2007whileinMarylandtolearnofhisworkanddiscussthefundamentalsofterrapinbiologywithWillemandsomeofhiscolleagues.Herein,wedescribewhatwelearnedandexperiencedduringthattime.

Natural history of Diamondback ter-rapins

Diamondbackterrapinsliveinestuarine,brackish water habitats. The salinity theyexperience may vary considerably with

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Fig.2.CarapaceviewofaNorthernDiamondbackterrapin.Photo:B.Pfau.

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Fig.3.Malaclemys terrapin terrapinfemalewithaskinpatternofsmallspots.Photo:B.Pfau.

Fig.4.Malaclemys terrapin terrapinfemalewithaskinpatternofboldstripesanddots.Photo:B.Pfau.

Fig.5.Male(left)andfemale(right)terrapinsshowthedifferenceintailshape.Photo:B.Pfau.

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fluctuationsinrainfallandthestageofthetide.Terrapinsareadaptedtothesefluctu-ations and can tolerate a certain range ofionconcentrationsintheirbodyfluids,butthecompositionoftheirintracellularfluidsremainsfairlyconstant(roBinSon & DunSon1976). If the salinity of the water is highforseveraldays, thenterrapinsmaytrytoaccessfreshwater.Theywillwanderontolandanddrinkwaterfrompuddlesorevenfromathinwaterfilmonthesoil.Inrainyweather,theycanobtainwaterthatrunsofftheircarapace(DavenPort & maCeDo1990).Terrapinsdohavelachrymalglandswhichliebehindtheeye,buttheseglandsarenoteffectiveinregulatingtheosmoticpressureoftheirbodyfluids(CoWan1990).

Unfortunately, most estuaries along theeast and Gulf coast of the United Statesaremajoragricultural,industrial,andurbanareasandthussufferfromavarietyofanthro-pogenicdisturbanceincludingpollution,ha-bitatdestruction,andinteractionwithfishinggear.Naturally,diamondbackterrapins,like

otherestuarineorganisms,areaffectedbythepollution.Heavymetals,includingmercury,accumulateinthetissuesofturtles(seeforexampleBurger2002).Blainvillain et al.(2007)suggestedthatdiamondbackterrapinscan be used to monitor pollution, becausetheybioaccumulatetoxicsubstanceswhichtheyobtainviathefoodchain.Organiccon-taminantsalsoharmterrapins.DiamondbackterrapinsexposedtoPCBshowhigherstresshormonelevels,slowergrowthandreducedbonedensitythancontrols(forD 2005).Oilspills in coastal areas affect diamondbackterrapinsdirectlybyoilinganddrowningtheanimalsandindirectlybycontaminatingtheirnestingbeaches.Theshort-termimpactsoftheoilspillfromaleakinanundergroundoil pipeline near Chalk Point, Maryland,areratherwelldocumented(NOAA2000).Researchshowedthatnotonlytheterrapinsthemselves,butalsohatchlings fromnestsin polluted sand were severely affected(rooSenBurg et al. 2001). Regrettably,and as usual, there has been no long-term

Fig.6.FemaleMalaclemys terrapin.Photo:B.Pfau.

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survey of the impacts of this oil pollutionon the Diamondback terrapins and otherorganisms.

Terrapinsarepredominantlymolluscivo-resfeedingmostlyonsnails,barnacles,andclams.Adultsalsowilleatcrustaceansandfisheswhentheycancatchthem.Juvenilespreyonsoft-bodiedanimalsincludingsmallcrustaceansandinsects,forexampleamphi-pods(Amphipoda)orgreencrabs(Carcinus maenas;king2007).Largerfemaleterrapinsare specialized; they mainly feed on hard-shelledpreybecauseoftheirabilitytocrushtheshellsofmanygastropodsandbivalves.Dietvariesdependingontheavailabilityofprey, in areas where snails are uncommonterrapinsfeedmostlyonsoft-shelledclams(Mya arenaria) and mussels (Mytilus sp.),but where snails are abundant they are in-cluded in thediet. In the southernpartsoftherangetheypreyontheMarshperiwinkle(Littorina irrorata; seetuCker & fitzSim-

monS1992,tuCker et al.1995).Thissnailfeedsonbacteriathatgrowonecologicallyimportant cordgrass (Spartina alterniflora)andheavygrazingbythesnailsdamagesthestems. Spartina plays an important role inshorelinestabilizationanditslossincreaseserosionrates.Conservationistsappreciatetheecologicallyimportantroleoftheterrapinsasperiwinklepredators.Theterrapinswalkorswimbetweenthecordgrassandpluckthesnails,andcrushtheirshellswithandaudiblepopping noise (see for example Conant & neWman1993).

Similar to females of some Graptemysspecies, the sister genus of Malaclemys,female terrapins have enlarged heads andbroadcrushingsurfacesoftheirjawsadaptedto their hard-shelled prey (lamB & oSen-toSki1997).Fullygrownmaleterrapinsdonotshowheadenlargement,andtheyarenotable tocrushmolluscswithheaviershells(tuCker et al.1995).

Fig.7.FemaleMalaclemys terrapin.Photo:B.Pfau.

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N O R T H

P A C I F I C

O C E A N C A R I B B E A N S E A

B E A U F O R T

S E A

LABRADOR

A R C T I C O C E A N

Gulf of Mexico

Gulf of California

Gulfof

Alaska

Middle America Trenc

PanamaCanal

MackenzieBay

CoronationGulf

Queen MaudGulf

AmundsenGulf

FoxeBasin

KaneBasin

HudsonBay

JamesBay

UngavaBay

Gulf ofSt Lawrence

McClure Strait

Prince Albert Sound

Dolphin and Union Strait

Princ

e ofW

ales St.

Viscount MelvilleSound

HazenStrait

Jones Sound

Lancaster Sound

CapeYork

P a r r y C h a n n e l

McClintock Channel

Frank

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Comm

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B a � nB a y

Austin

Atlanta

New York

HoustonNewOrleans

Boston

WASHINGTON

Columbia

Miami

St Louis

Chicago

Dallas

Memphis


Fig.8.DistributionmapofthesubspeciesofMalaclemys terrapin(afterernSt et al.1994).

Diamondback terrapins also eat crus-taceans, particularly fiddler crabs (Uca pugnax andother Ucaspecies),marshcrabs(Sesarma reticulatum)andbluecrabs(Calli-nectes sapidus;tuCker et al.1995).Becauselargercrabshavehardchitinexoskeletons,terrapinssometimeswilleatonlythecrab’slegs,despite their lowernutritionalvalue.Tocropacrableg,theterrapinattacksthecrabfrombehindandtakesthelegfarthestfrom the pinching chelipeds, and tries totrick thecrab intodropping it (DavenPortet al.1992).Terrapinsalsopreferbluecrabswhentheirshellsaresoftaftermolting.

Ageandsizeatmaturitythroughouttheterrapinsrangevariesconsiderably.Ingene-ral,bothageandsizeatmaturitycorrelatespositivelywithlatitude.InChesapeakeBaymale terrapinsmatureat4-5yearsofage,10 cm straight plastron length (SPL) anda weight of 300 g. Females start laying

eggsatabout8yearsofageandaSPLof16.5 cm, and a weight of at least 1,100 g(rooSenBurg1996).

There is considerable variation in thereproductiveoutputofterrapinsthroughouttheir range. In general, females maturelater and at a larger body size, producelargerclutchesofsmallereggs,andhaveashorter nesting season as one goes north.The variation is considerable when onecompares populations in Florida to thosein Massachusetts (rooSenBurg 1994).Fundamentaldataonterrapinreproductionin Maryland has been gathered from boththe Patuxent River and the Poplar Islandresearchproject(seebelow).

Like most other chelonians, Diamond-backs exhibit temperature dependent sexdetermination(TSD;JeyaSuriaet al.,1994).Whenincubatedatconstantconditions,thetemperatureduringthemiddlethirdofincu-

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Fig.9.Diamondbackterrapinnestingbeach.Photo:B.Pfau.

Fig.10.FormerDiamondbackterrapinnestingbeach,nowwithhousesandgardens.Photo:B.Pfau.

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Fig.11.Fema-leMalaclemys terrapin.Photo:B.Pfau.

Fig.12.Fema-leMalaclemys terrapin,portrait.Photo:C.Pfau.

Fig.13.Fema-leMalaclemys terrapin.Photo:B.Pfau.

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bationdeterminessex.Warmtemperaturesproducefemales,cooltemperaturesproducemales and 29.1 C produces a mixed sexratio(JeyaSuriaet al.,1994).Thethresholdrangethatresultsinmixedsexratiosisonlyabout3°Cwide.Femaleterrapinswillplacelarger eggs inwarmer environmentsmorelikelytoproducefemalesandsmallereggsin cooler sites. Coupled with the sexualdimorphism in terrapins the behaviour ispotentially adaptive because female off-spring from larger eggs grow faster andmature earlier than those fromsmall eggswhereas males do not realize a differencein growth or age at maturity attributabletoeggsize(rooSenBurg & kelley1996).Thereforeitisadvantageous(adaptive)forfemales to lay largereggs inwarmersites(rooSenBurg1996).

Furthermore, these finding suggest thata variety of beach habitats are needed tomaintainafunctionalmale-to-femaleratioinagivenpopulation.Forexample,ifonlysouthfacing,warmerbeachesthatarefemalebiased, are protected, then sex ratio skewmayoccur(rooSenBurg & PlaCe1995).

Theminimumincubationtimeinthela-boratoryis40days(rooSenBurg & kelley1996). In the wild incubation times rangefrom50days,towellover200daysassomehatchlings, mainly from “late” nests, areable tooverwinter in thenest.Overwinte-ringnests hatch in the fall andhatchlingsremaininthenatalnestuntilthefollowingspring when they emerge. There they canexperience subzero temperatures in thenests but they have the ability to survivethesub-zerotemperatures(CoStanzo et al.2006). However, severe cold and prolon-gedfreezingwillincreasethemortalityofoverwinteringhatchlings.

Diamondback terrapins are vulnerableto a variety of predators throughout theirlifecycle.Nestsaredepredatedbyseveralspecies of mammals including racoons,

foxes,skunks,andottersthateattheeggs.Avianpredator(seagulls,crows,andwillets(Catoptrophorus semipalmatus, rooSen-Burg personal observation) also prey onterrapin nests. Additionally, king snakes(Lampropeltis getulus, rooSenBurgpersonalobservation) eat terrapin eggs.On severalbeachescrowshave learned towatchnes-ting females and eat their eggs, sometimewhilethefemaleisstilllaying.Evenplantrootscanbedangeroustoterrapineggsandembryos.Theyareattractedtothemoistureandnutrientsandsurroundtheeggstightlyandabsorballthemoisturefromtheeggandinsomecases therootsentrapahatchlingandpreventitfromemerging(rooSenBurg1992,giamBanCo2003,Butleret al.2004).Abiotic factors, including floodingduringstorms and prolonged drought, may alsoleadtonestfailures.

Hatchlingsarealsovulnerabletopreda-tion. Some nests are attacked by ants andafter leaving thenesthatchlings are eatenbymanypredators,includinggulls,herons,cormorants,crows, raccoons, foxes,ottersandrats.

Reachingthewater,theyfacemorepre-datorssuchas largefishandcrabs(whichtheyinturnliketoeatwhengrownup).Toavoidpredationthesmallerterrapinsliveinmarshesneartheshorelinehiddeninshallowwaterwithplentyofcoverandvegetation(seerooSenBurg et al.1999).

Adultdiamondbackshavefewernaturalenemies.Unfortunately,someracoonshavelearnedtowaitforfemalescomingashoretonest.Theykillthembyseveringtheheadand thendisemboweling themthrough theinguinalopeningof the shell toget to theeggs.TerrapinsshellsalsocanbefoundnearthenestsoftheUSA’snationalemblem;thebaldeagle(Haliaeetus leucocephalus)willeatmalesandhalfgrownfemaleterrapins(Clark 1982), but it is unknown if theseterrapinsarekilledorscavenged.

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Fig.14.AlargeHorse-shoecrab(Limu-lus polyphemus).Photo:C.Pfau.

Diamondback terrapin subspecies and distribution

Diamondback terrapins, Malaclemys terrapin (SChoePff 1793),occuralong theAtlanticandGulfcoastsfromtheNewEng-landstatestosouthernTexas.Traditionallytheyhavebeendividedintosevensubspeciesthroughouttheirrange(Carr1952,ernStet al.2000,Fig.8).However,recentmolecularstudiessuggestthedistinctionbetweenthesubspecies is not clear (see for exampleChanet al.2006).The traditionalsubspe-ciesbasedonmorphologicalcharacteristicsincludethefollowing.

Malaclemys terrapin terrapin (SChoePff 1793), Northern Diamondback terrapin,ranges along theAtlantic coast from CapeCodtoCapeHatteras.Itsmedialkeeldoesnotbearterminalknobsoneachscute,andthesidesofthecarapacedivergeposteriorly.

Malaclemys terrapin centrata (latreille 1802), Carolina Diamondback terrapin,rangesfromCapeHatterassouthalongthecoast to northern Florida. Its medial keelbearsnoterminalknobsoneachscute,thesides of the carapace are nearly parallel,andthemarginalscurlupwards.

Malaclemys terrapin tequesta (SChWartz 1955),theFloridaEastCoastterrapinoccursalongtheAtlanticcoastofFlorida.Itsmedialkeel bears posteriorly facing tubercles orknobs.Thecarapaceisdarkortanwithnopatternofconcentriclightcircles.

M a l a c l e m y s terrapin rhizo-

phorarum (foWler 1906), the MangroveterrapinisrestrictedtotheFloridaKeys.Itsmedial keel bears bulbous terminal knobsanditsshellisstronglyoblong.Theventralseamofthemarginalandplastralscutesareoftenoutlinedwithblack.Spotsontheneckfrequentlyfusetoformastreakedpattern,andthehindlegsmaybestriped.

Malaclemys terrapin macrospilota (hay 1904) the Ornate Diamondback terrapinrangesalongtheGulfcoastfromTampaBaytothepanhandle.Itsmedialkeelhastermi-nal,oftenbulbous,knobsandthecarapacialscutesshoworangeoryellowcenters.

Malaclemys terrapin pileata (WieD-neu-WieD 1865), the Mississippi Diamondbackterrapin ranges along the Gulf coast fromtheFloridaPanhandletowesternLouisiana.Its medial keel has terminal tuberculateknobs. The scutes of the oval carapacelack light centres. The upturned edges ofthemarginalsareorangeoryellow,andtheplastronisyellowandoftendusky.Topofthe head, upper lip, neck, and limbs areblackordarkbrown.

Malaclemys terrapin littoralis (hay 1904), the Texas Diamondback terrapinoccurs along the Gulf coast from westernLouisiana to Texas and has a medial keelwithterminalknobsonitsdeepcarapace.Itscarapacialshieldslackdistinctlightcentres,theplastronispaleorwhite,theupperlip

and top of head are whitish, andthe neck and legs are gree-

nishgraywithheavyblackspotting.

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Fig.15.OldbarnnearthePatuxentriver.The“laboratory”forDiamondbackterrapinresearchisinthegroundfloor. Photo:B.Pfau.

Fig.16.Fykenet.Thebackendofitisalwaysabovethewaterlevel.Photo:C.Pfau.

Fig.17.Bluecrab(Cal-linectes sapidus).Photo:B.Pfau.

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Fig.18.ThisSnappingturtle(Chelydra serpentina)wasimmediatelyreleased.Photo:C.Pfau.

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A comprehensive, well illustrated sy-nopsis of the Florida subspecies of Ma-laclemys terrapin is given by Butler et al. (2006).

Diamondbacks terrapins also occur inBermuda(DavenPortet al.2005).Parhamet al. (2008) tested the origin of theseterrapins using a combination of paleon-tologicalandgeneticdata.Theyconcludethat the terrapinsare recentnatural colo-nizers,between3,000and400yearsago.ThesubspeciesoftheBermudaterrapinsisnotgivenbuttheysuggestthatitiseitherM. t. terrapinorM. t. centrata.

TerrapinswereintroducedinCaliforniain1886andagainin1943butthesepopula-tionsdisappearedshortlyafterintroduction(BroWn1971).

Diamondback terrapins of unknownorigin cannot be reliably identified tosubspeciesasbasedontheirexternalcha-racteristics.However,geneticanalysiscanidentify populations and have been usedto identify the source of terrapins fromthe markets in New York City (leSter 2007).

Becauseterrapinshavebeentradedsin-cethe1800’sandthereareknowescapesand releases throughout their range, it ispossible that many populations containsubspecifichybrids.

Threats to Diamondback terrapinsNumerousauthorshavedescribedthreats

to terrapin populations throughout theirrange(Florida, Butler et al.2006;Mary-land,rooSenBurg1991;NewJersey,WooD & herlanDS1997;andrangewide,Seigel & giBBonS 1995). These threats includecommercialharvesting,bycatchmortalityin commercial crab pots, loss of nestinghabitat, impactsbycarsandmotorboats,pollution,andtheincreaseinpredationofnestsbygrowingraccoonpopulations.

Crab potsPerhaps the biggest threat to terrapins

throughout their range is the interactionwiththecommercialbluecrab(Callinectes sapidus)fishery.Themostpopularmecha-nism to catch crabs in most states is thecrabpot.Crabpotsfunctionsimilartoturtletraps,howeverbecausetheyfishsubmerged,entrapped turtles most often drown. Othermechanisms to catch crabs include banktraps, trot lines, and crab traps. However,if fished properly these techniques do notleadtoterrapinmortalityinasimilarmannertocrabpots.

Becausecrabpotsare theprimarycom-mercialwaytoharvestcrabs,trappingeffortcan be concentrated and occur in shallowwaterswhereterrapinsoccur.Furthermore,potsarebaitedwith fishwhichattract ter-rapins, and at times clams are sued a baitwhichareapreferredfoodofterrapins.

rooSenBurg et al. (1997) examined theimpactofcrabpotsintheChesapeakeBay.They estimated that 15-78% of the localterrapinpopulationscanbecapturedincrabpotsinasingleyear.Becausetheentranceofthepotsistoosmallformaturefemales,mostofthevictimsaremalesandsimilarlysizedfemales.Verysmallterrapinscanescapethepotsthroughthewiremesh.Becauseoftheselectivemortalityofmalesincrabpots,theterrapinsexratioinChesapeakebayis1:2to1:3(m:f).Thus,crabpotshaveaneffecton the population structure and long-termimpactsonthepopulationdynamics.

Roosenburget al.(1997)designedanew,larger,crabpot thatmaintainedpermanentaccess to air and prevented the drowningofterrapins.Theycomparedthecatchratesof thenewpots to the traditional size andactually caught more crabs in their newdesign. Nevertheless the higher costs andcumbersomesizeofthemodifiedpotspre-ventedtheircommercialsuccess.

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Fig.19.PalpatingafemaleDiamondbackterrapinforeggs.Photo:C.Pfau.

Fig.20.Measuringcarapacelength.Photo:B.Pfau.

Fig.21.Measuringthelengthofthesutureofthethirdplastronshieldontherichtsideoftheterrapin.Photo:B.Pfau.

Thenextdevicetobetestedwasthebycatchreductiondevice(BRD)thatpreventsterrapinsfrom entering the pots (WooD & herlanDS,1997). Several authors have tested BRDs ofvarioussizesandinavarietyofstates(reviewedin rooSenBurg 2004).All studies have beenabletopinpointthedimensionsofaBRDthatgreatlyreducesterrapincatchwithoutreducingcrabcatch,e.g.rooSenBurg & green(2000), Butler & heinriCh(2007)andCole & helSer(2001).InMaryland,themosteffectivebycatchreduction devices are rectangular frames ofwireorplasticmaterialwithopeningsof4.5cm by 12.0 cm, which are fitted horizontally intothepotentrance.Thedevicesreducedtheterrapin bycatch by 82% and did not affectthecrabnumbersorsizeofthecommerciallyvaluablecrabs (seeforexample rooSenBurg& green2000, raDzio & rooSenBurg2005,Butler & heinriCh2007).

Habitat lossFemaleterrapinsprefersandysubstrates

for nesting (Fig. 9). Coastal populationsprefer to nest on sand dunes (Burger & monteveCChi 1975) while females frominlandpopulations,wheredunesareabsent,nest on beaches and sandy fringes of theestuary.These nests are usually less than10 m from the mean high tide mark andin some cases can be inundated by winddriven,higherthannormaltides.Unfortuna-tely,waterfrontpropertyisinhighdemandthroughoutoutmuchoftheterrapin’srange.Landowners resort to bulk heading andthe use of riprap to prevent loss of theirproperty. These structures form barriersthat prevent terrapins from reaching theirpreferred nesting areas and results in thelossofnestinghabitat(rooSenBurg 1991, rooSenBurg & PlaCe1995).Furthermore,

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Fig.22.Femaleterrapinshaveenlargedheads.Photo:B.Pfau.

Fig.23.Markingofater-rapinwhichwascaughtforthefirst time. The woundswhicharecausedbyboringthemar-ginalshieldswillhealupquickly.Photo:B.Pfau.

Fig.24.Theterrapinisreleasedcareful-ly...Photo:C.Pfau.

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thehousesareusuallybuiltneartheshore(Fig. 10), or the owners create lawns orornamentalgardensthataltertheincubationenvironmentandaremaintainedintensive-ly resulting in thedeathofmany terrapinhatchlings. Additionally the access roadstocoastaldevelopmentsareoftenbuiltonhighgroundthatisterrapinnestinghabitatcreatingperilsfornestingfemales,particu-larly if theychoose theroadembankmentasanestsite(WooD & herlanDS1997orSzerlag & mCroBert2006).

Additionallyracoonpopulations(andinsome places also fox populations) thrivewithincreasinghumanpopulationsbecauseour garbage provides a dependable foodsource year round. The concentration ofnests as nesting habitat becomes limitedcombined with increasing raccoon popu-lations results in high predation rates onnesting beaches, frequently over 90%.Racoonsandfoxesareexcellentatfindingand depredating turtle nests resulting inverylowrecruitmentinareaswherethesepredatorsoccur.

Commercial exploitationUp until the beginning of the 20th cen-

tury,Diamondbackterrapinswereingreatdemand by gourmet restaurants in majormetropolitan areas of the US. haramiS et al.(2006)detailthemosteffectivemethodof harvesting Diamondback terrapins,dredgingorscrapinginhibernaculawhereterrapins congregate during the winter.Harvest rates using this technique can beas high as 200 adult terrapins per hour.Terrapins congregate in large numbers inshallow, sheltered creeks in ChesapeakeBaytohibernateinareaswheretheycanbeharvestedeasilywithspecialdredges.Testdredgingsrevealedthatmostoftheanimalscaught were adult females, suggesting asignificant reduction in the population’sreproductivepotential.Duringtheterrapin’s

activeperiod,fykenetsarethemosteffec-tiveharvestingmethod.

In1920,theprohibitionledtoadeclinein the demand for terrapin flesh becausea key ingredient of terrapin soup wassherry.Thiscontributedtotherecoveryofterrapinpopulationsasthemarketdemandevaporated(compare thechapter“AClearandPresentDanger”inBrenneSSel2006).Nevertheless, the harvest continued on asmaller scale and the terrapin stews werecooked according todifferent recipes, butintheU.S.theterrapinslowlydecreasedinvalueasfood,andnolongerwasconsideredadelicacy.Duringthe80’s,arisingdemandforterrapinsintheChinatownsofthelargerUSandCanadiancitiesfuelledincentiveforfishermentoagainpursuetheterrapin.

Furthermore, in 1989 China opened itsmarketsfortheinternationaltradeandtheterrapinfisherybegantoincreaseconspicu-ously.Animalswereexportedliveingreatquantities. One single fisherman reportedthathehadcaughtandsold5,000in2006,and that half of those were exported toChina. Another exporter advertised thathecoulddeliverone tonofdiamondbackspermonthtoChina(CheSaPeake terraPin allianCe,seeInternetresources).

In2007,thelasttwoUSstates,MarylandandTexas,thatpermittedlargescaleharvestpassedlawsstoppingthecommercialharvestofwildterrapinsforbothfoodandthepettrade(seebelow).

Diamondbackterrapinsarestillingreatdemandaspetsforturtleaficionados.Ter-rapinenthusiastsandthepettraderecognizethatcaptivebredterrapinsaresuperiorpetsbecausetheyarelesspronetodiseasesthanwildanimals.Additionally,prohibitiononcommercial harvest limits the availabilityofwildanimalsforthepetindustry.IntheUSA, there are some speciality terrapinbreeders for the pet market. In Europe,there are only few Malaclemys groups

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beingkept, andaccordingly fewbreedersregularlyhatchthem,buttheyareavailablethroughsomesources.

Diamondback terrapin conservationLegislationIn 1994, the diamondback terrapin be-

cameMaryland’sofficialStatereptileandfor 70 years has been the University ofMaryland’smascot.TheMaryland Depart-ment of Natural Resources is responsiblefor controlling research and promotingterrapinconservationandmanagement.Inthelast10years,decliningterrapinpopu-lationsandcontinuedcommercialharvestspawned a renewed public awareness ofdiamondbackterrapinsfocusedonclosingthe commercial harvest and improvingconservation.Forthemostpart,thepublicwasunawareoftheexploitationofnaturalterrapinpopulations.

Finally,inJuly2007,Marylandbannedthe commercial harvest of diamondbackterrapins. The governor of Maryland si-gned the “Terrapin Bill”, and only Texasremained as the one state in the rangeof Malaclemys terrapin where terrapinscouldbeharvested.Texasadoptedsimilarlegislationbanningthecommercialharvestmostspeciesofturtlesincludingterrapinsaboutonemonthlater.

New Jersey, Maryland, and Delawarehave laws and regulations requiring theuseofBRDsoncrabpots.However,moststates in the terrapins range do not haveregulationsthatprotectterrapinsfromthecrabpots.NewJerseyandGeorgiarequirerapidlydecayingpanelsmadeoffastrustingmetals) to allow escape from lost traps(ghostpots).Ghostpotscontinuetocatchterrapins and have frequently been foundwith more then 50 terrapins in a singletrap (rooSenBurg 1991).An overview ofthelawsandregulationsforcrabpotsaregivenbyWatterS (2004).

PublicityDiamondbackterrapinsareanexcellent

hallmarkspeciesfortheprotectionofthefragile estuarine environments. Youngchildrenaredrawntohatchlingsandwillengagethemselvesfortheirprotectionand,ifwell informed,will involve their fami-liesandfriends.Thisiseffectivebecausenobody will act directly against the willofanangrychild!

Therefore conservation efforts ofteninclude children. Of special importanceforDiamondback terrapinprotectionwastheprintingofthechildren’sbook“Turtlesinmysandbox”,byJenniferKeatsCurtiS(2007).Theauthordepictshowalittlegirllearns toobserve terrapinshatching fromeggs that she had found in her sandbox.Thestorydescribeshowshedevelops,withthe help of a neighbour, into an engagedterrapinconservationist.

Children also desire to be actively in-volved.Conservationprojectsthatinvolvehead-starting and releasing terrapins atlarger body sizes are a good opportunitytoworkwithschoolchildren.Thechildrencareforterrapinsintheirclassrooms,andcollectdataontheirbehaviourandgrowthas part of a curriculum to teach envi-ronmental biology. Used correctly, theseterrapins engage children in the broadercontextofenvironmentalstewardshipandenvironmentalawareness.

Raising terrapin hatchlings acceleratesgrowth to a larger, body size while thechildren incorporate terrapin themes intheir curriculum.The children frequentlyproject theirenthusiasmfor terrapincon-servationtofriendsandfamily.

Precautionsarenecessarywhenchildrenwork with turtles because they can carrySalmonella or other bacteria. Therefore,detailedinstructionsonterrapinhusbandryweredevelopedandsomeofthetasksarecarried out only by adults. Children are

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Fig.25.…andswimsawayasrapidlyasitcan.Photo:B.Pfau.

not allowed to touch the terrapins – thisisgoodtrainingforhandlinganywildlife.Children change the water and clean thefilters according to specific instructions.Onlyonthereleasedaymaythechildrenhandle“their”terrapinwhentheyletitgo(andwashhandsimmediatelythereafter).

Terrapin attract considerable mediaattention in local newspapers and onTV.Children with animals always have greatpublic appeal; see for example gvozDaS(2007a, b). The children sensitize thepublic to terrapin conservation and theycontributed to raising public awarenessaboutthebillbanningcommercialharvestinMaryland(seeabove).

InMaryland,onehead-startingprojectis coordinated by Will WilliamS andSteve Barry (Fig. 1) at the Arlington Echo Outdoor Education Centre.Terrapinhatchlings from Poplar Island are used

in their program (see below). Teacherssubmit weekly reports on the terrapins’measurements to Will who maintains thedatabase.TheprojectgetspublicfundingfromtheChesapeakeBayTrustwhichpaysfor aquaria, food, and measuring tools.Will organizes buses and boat trips thatbringthechildrentoPoplarIslandforthereleaseof“their” terrapins.

Since1932, thediamondback terrapin,“Testudo”hasbeentheofficialmascotoftheUniversityofMaryland.TheUniversityof Mayland “Terrapins”, or “Terps” playunder the motto “Fear the Turtle”. Since2002, the university contributes 15% ofthe proceeds derived from the sales ofmaterials bearing the “Fear the Turtle”logo to terrapin conservation and educa-tion.Thesefundsareusedtofundterrapinresearch and interns working on terrapinconservation.

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Fig.26.Thisbaldeaglehasitsnestveryneartothe“laboratory”.Photo:C.Pfau.

Fig.27.JuvenilefemaleterrapinfromPoplarIslandwithcarapaceanomalies.Photo:B.Pfau.

Scientific research on Diamondback terrapins in Maryland

In 1987, prior to becoming Maryland’sstatereptile,WillemrooSenBurgstartedhisresearch on Malaclemys terrapin terrapinintheMarylandwatersofChesapeakeBay.Hespendshisspringsandsummersstudyingterrapinson the lowerPatuxentRiverandlivinginasmallhouseonCremonaFarm.Several studentsworkwithhimeachyearcontinuing his mark-recapture study andcompleting their own research projectsunder his supervision. The students liveinprimitivebunkhousesonCremonathatare part of the research facility.A groundfloorroominanoldeast-coastbarnservesas a “laboratory” for processing terrapins(Fig.15).

Theprojectsundertakeninthisresearcharecomprehensive.Thecornerstoneoftheterrapinresearchis thedemographicworkthat has developed a 23 year database ofover10,000terrapinsandmorethan31,000captures.

Long-term research of the lower Patuxent River Diamondback terrapin population

Terrapinsarecaughtinvarietyoftraps,but most are caught in unbaited fyke netsthataresetneartheshore(Fig.16).Afloatholds the cod end above water, maintainsan airspace that will adjusts with the tideso theentrapped terrapinswillnotdrown.Thenetsarecheckeddailytoavoidharmingtheterrapins.

The nets also catch a host of estuarineorganisms, including a variety of fishes,horseshoecrabs(Limulus polyphemus,Fig.14), blue crabs (Callinectes sapidus, Fig.17) and snapping turtles (Chelydra ser-pentina, Fig. 18).The bycatch is releasedimmediately.

Female diamondbacks are immediatelypalpated for eggs (Fig. 19), and if gravidtheyareseparated from theothers incasethey start to lay their eggs before beingreleased.Theterrapinsareheldinnumberedlaundry bags and the location of the trapandbagnumberarerecordedtoensurethat

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animalsare returned to thesame location.After checking all the nets, the terrapinsare brought back to the “laboratory” forprocessing.

Researchers measure carapace length(Fig.20),carapacewidth,carapaceheight,plastron length, length of the 3rd midlineseam of the left pectoral scute (Fig. 21)andheadwidth(Fig.22).Researcherscountgrowthannulitoagetheterrapinandtheter-rapinisweighed.Finally,studentsdeterminethegenderofterrapinsgreaterthan10cmcarapacelength.IftheterrapinhasalreadybeenmarkedtheIDisreadandcheckedinthedatabase,otherwisetheanimalismarkedusing the traditional notching of marginalscutes(Cagle,1939;Fig.23).

Upon completion of processing the dayscatch, the terrapinsarebroughtbackandre-leasedwheretheywerecaught(Figs.24and25).Theyswimonlyashortdistance,thendivedownandafewsecondslater theyresurfaceforabreathandaseemingorientationoftheirwhereabouts.

The diamondbacks in the research areahavebeenrecapturedonaveragethreetimes.Theoldestterrapincaughtin2007was32years, a female first caught in1987whenshewastwelveyearsold.Terrapinscanbeageduntilabout10-15yearsafterwhichtheannulifadebecausetheyshedthescutesthatrevealtherings.Thisfemalewasstillheal-thywhencaughtin2007andwasperhapsonherwaytoanestingbeach.Themaximumage of wild Diamondback terrapins is notyetknown;onlythecontinuingstudieswillrevealthepotentiallongevityofterrapins.However, it is reasonable to assume thatsomefemaleterrapinsinthePatuxentRiveraremorethan50yearsold.

Mostoftheterrapinscaughtinthefykenetsare females(sexratio3-3.5:1).Otherpopulation studies in the Chesapeake Bayhavesimilarresultsandrevealthatthereareconsiderablymorefemalesthanmales.

TheterrapinnestingseasoninChesapea-keBaybeginsintheendofMay(MemorialDayisagoodreminder)andcontinuesuntilthe end of July. On rare occasions, nestshavebeendiscoveredinAugust.TheaverageclutchsizeinthemiddleChesapeakeis13eggsandfemaleswillnestupto3timesperyear(rooSenBurg & Dunham1997).

The long-term study alsobenefits fromserendipitous observations. For example,the shells of marked terrapins have beenrecovered under an active bald eagle nestthatisnearthe“laboratory”(Fig.26).

Thelong-termresearchrevealssomeinte-restingfindings.Diamondbacksmovelittleamongregionsofthebay.Recaptureratesofadultsarehighandfemalesshowahighdegreeofphilopatry tonestingareas.Thelimitedmovementmaycontribute tomor-phological differences among populationsthroughoutthebay,e.g.femaleterrapinsonSmithIslandhavebroaderheadsandsmallerbodysizessuggestingthatthepopulationstheir may have larger beaks because theyfeedonhardershelledsnailsthentheclamspreferredinthePatuxentRiver.Adetailedanalysisisneededtoconfirmthedivergencebetweenthesenearbypopulations.

Regrettably rooSenBurg’s long-termstudy documents a decline in the terrapinpopulationinthePatuxentRiversince1996.Becauseofthecomprehensiveandreliabledocumentation,thisresultcannotbedeniedby the lobbyists of the commercial turtleharvesters or the industries that pollutethe habitat. Only prudent environmentallegislation protecting terrapins and theirhabitatandstringentenforcementcoupledwith public awareness could perhaps re-versethedeclineoftheterrapinsandotherorganisms in the fragile estuarine habitat.Although some progress toward this goalhasbeenaccomplished,muchremainstobeimplementedtoensureterrapinpopulationsforfuturegenerations.

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Diamondback terrapin habitat resto-ration on Poplar Island

Sandyislands,idealnestingbeachesforterrapins,wereoncecommonthroughouttheChesapeakeBay.However,inthelastcen-turyacombinationofdevelopment,erosion,andincreasingwaterlevelshavediminishedtheseislandsthroughoutthebay.Duringthelast century mean high water marks havechangedasmuchas40cminsomeareas.The accompanying loss of marsh habitatshasbeenparticularlywelldocumentedforthe“BlackwaterNationalWildlifeRefuge”inMaryland(USGS2004).

PoplarIslandliesapproximately50milessouthofBaltimoreneartheeasternshoreofthebay.Whenoriginallymappedin1847,PoplarIslandwasmorethan400hectares.Becauseofitsisolationandbeauty,theis-landbecameaweekendretreatforprominentpoliticiansin1930sandthereforegainedno-toriety.By1999lessthan5acresremained.The availability of dredged material fromtheshippingchannelandBaltimoreHarbourapproach provided a potential source torebuild the island. An interagency group,includingtheU.S. Army Corps of Engineers,the Maryland Port Administration, andFederal and State environmental agenciesdecidedin1994tore-buildPoplarIslandtoitsoriginalsizeusingdredgedmaterial.In1999thetaskbeganandwillbecompletedin2016.AsummaryofthisprojectisgivenontheinternetsiteoftheuS army CorPS of engineerS(USACEw.y.).

The restoration project is monitoredclosely,includingdetailedanalysisofwaterquality,dredgematerial,andtheimpactonlocalwildlife.Astheprojectprogressestheimpactson the islandsfloraandfaunaarecarefullymonitored to assure the creationof high quality habitat. Like many otherwildlife species, terrapins started usingPoplarIslandassoonasthefirstdikeswereconstructed. It remains unknown whether

these were old resident females native tothe archipelago and nested on the islandsbeachesinpreviousyears,orwhethertheycamefromthemainlandanddiscoveredthenewbeaches.Thehatchingsuccesson thenewbeachesisexceptionallyhigh.However,theterrapinsarenestinginsandminedfromthesiteandnotindredgematerial.

Althoughtheengineerswhowouldhavepreferred that the terrapins wait until theisland was completed, and measure werenecessary to keep terrapins from enteringareas still under construction.For the ter-rapins,theislandisatremendoussourceofrecruitmentbecausenestpredators,racoonsand foxes, have not colonized the island.Therefore,over70%ofterrapinnestssur-vive.Onlythefishcrows, Corvus ossifragus,gulls,Larus spp.,egrets,Egrettaspp.,andherons Ardea spp. are still a threat to thenestsandhatchlings.

DiamondbackterrapinsinhabitedPoplarIslandinthepast.Butastheislanderoded,the terrapin population probably declinedbecause the nesting beaches were succes-sively lost and the shallow water habitatswere flooded. One of the most importantgoalsoftheprojecthasbecometherestora-tionoftheresidentterrapinpopulation.

Poplar Island is surveyed annually byterrapin specialists (see for exampleroo-SenBurg & allman 2003, rooSenBurg et al.2003,2004,2007).

Insummer2002,thestudyteamfound50terrapinnestsandrecovered323hatchlings.In2006,morethan280nestswerediscoveredand1616hatchlingswereproducedon theisland (rooSenBurg et al. 2007 and rooS-enBurg 2007, see Internet resources). Theincreaseinnestingobservedduringthelastfive years suggests that the island is goodnestinghabitatthatmaybelimitinginotherareasofthebaybecauseofshorelinedeve-lopment.AtthePatuxentRiversite,terrapinsaverage 13 eggs per nest (rooSenBurg &

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Fig.29.WillemrooSenBurg sexesaterrapin.Photo:B.Pfau.

Fig.28.Theendoscopeisinsertedtroughaslitwhichhadbeencutintotheinguinalopening.Thelightoftheendoscopeshinesthroughthecarapaceapproximatelyatthelocationofthegonads.Photo:B.Pfau.

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Fig.30.Thejuvenileter-rapinsareraisedinstandardizedterraria.Photo:B.Pfau.

Fig.31.Atransponderisinserted.Photo:B.Pfau.

Fig.32.Theterrapinremainsinadryplaceuntilthewoundhasclosedsufficiently. Photo:B.Pfau.

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Dunham1997)butatthePoplarIslandsitefemales average almost 14 eggs per nest(Roosenburget al.2007).Researchersdonotunderstandthedifferencesbetweenthesetwopopulations that are separatedby less than50 km but future studies will explore whythedifferencesexistandtheenvironmentalfactorsthatunderliethem.

The hatchlings from Poplar Island aresamesizeasterrapinhatchlingsfromotherbeachesinMaryland.Scuteanomalies(ir-regular carapacial scutes, see for exampleFig.27)aremorecommononPoplarIslandand may be due higher incubation tem-peratures because the island lacks shadeproducing vegetation. High incubationtemperaturescausemorecarapacialanoma-liesinmanychelonianspecies(compareto JaSSer-häger & Winter2007),andalsointerrapins (herlanDS et al. 2003).There isno evidence that these anomalies reducetheturtlesfitness.

During the initial stages of the PoplarIslandRestorationProject,wetlandswherejuvenileterrapinsspendthefirstyearswerelimited. Nevertheless, the 2002 and 2003hatchlingswerereleasedintothebesthabitatavailable.Since2003,hatchlingsfromtheislandare released intonewlyconstructedwetland cells that are remarkable restora-tionsoftheestuarinesaltmarsh.

Since 2005, school classes through Ar-lingtonEcho(seeabove)havehead-startedapproximately450terrapinhatchlingsfromPoplarIsland.Thesehatchlingsattainthesizeof4-5yearoldsbyspringbecausetheyarefedandkeptinwarmconditionsthroughoutthe winter. This headstarting method hasbeenusedsuccessfully forcertain (notall)turtlespecies.The teachersare trainedandtherearingconditionsarestandardized.Theterrapinsliveinspecialaquariawith80×40cmbaseand10cmwaterdepth.Foamfilterscleanandagitatethewater.Astonebasking

Fig.33.WillemrooSenBurgdigsupthenest.Photo:B.Pfau.

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platformsitsunderfullspectrumfluorescentlightandaceramicheatbulb(Fig.30).Theterrapinsstartwithspecialpelletedfoodandgraduatetonaturalpreybeforerelease.Thewatertemperatureiskepthighintentionallytoacceleratedgrowthoverthewinter.

The teachers bring the terrapins to thelaboratoryinMayforanoverallexaminationandforsexingbyendoscopy(Figs.28and29).Theterrapinsaremarkedindividuallywith an internal PIT (Passive Integrated Transponder) tag (Fig. 31) and additionalgrowth data are collected. Following sur-geryandtagimplantation,theterrapinsarekeptdryfor12hours(Fig.32)toallowthe2 mm incision in the inguinal region toheal.Theteacherspickup“their”terrapins48hoursafterdropoff.Theschoolchildrenweantheterrapinstonatural,livefood,toteach the terrapins to forage in the wild.Crab and shrimp are “forbidden” becausetheyoungterrapinsgetaddictedtothisfoodandwillnotpracticecatchingworms,snailsandotheranimals.

Duringthelastdaysofschoolyear, thechildren come to Poplar Island to releasethehead-startedterrapins(seeabove,“Pub-licity”).Thesediamondbacksarenolongerdependentontheshallowwaterhabitatsandthey are too large for most of the naturalpredators.BecausetheycarrythePITtagswithanindividualcodetheirsurvivalcanbemonitoredinthefuture.Hopefully,someoftheseturtleswillnestonthebeacheswheretheyoriginated.

Electric fencing of nesting areasAsdescribedabove,theextensivedevel-

opmentalongbeacheshasreducedsuitablenestinghabitat,butalsoindirectlyincreasedthenumberofracoonsandfoxes,predatorsofterrapinnests.rooSenBurg(1991)foundthat35of1,314terrapinnestshatchedovera 4 year period. Most of the unsuccessfulnestswereeatenbymammalianpredators.

A more detailed analysis indicated thatpredation rates were higher on the beachwithahighernestdensity(rooSenBurg & PlaCe 1995) suggesting that nests preda-tion rates may be density dependent. Ifnest predation is density dependent, thencontinueddevelopmentandlossofnestinghabitatcouldresultingreaterthannormalratesofnestpredationandultimatelypopu-lationdecline.

Several techniques have been used toprotect chelonian nests including wirecages,transplantingnests,andchemicalstodetermammalianpredators.Mostofthesetechniques are laborious and expensive.Transplanting eggs runs the risk of dis-ruptingdevelopmentand therefore isonlysuggestedforcriticallyendangeredspecies.IncollaborationwithWillemrooSenBurg,undergraduatestudentsfromtheUniversityofMaryland’sGemstoneScholarprogramareexperimentingwith theuseof electricfencing to exclude mammalian predatorsfromnestingareas.

The researchers selected a recently re-stored nesting beach that formerly was aknownterrapinnestingarea(Fig.36).Therestoration used sand with higher gravelcontent than found on the typical nestingbeaches,butterrapinsarestillnestingonthesite.Spartinapatens wasplantedsparselyon the nesting area. marJorie ClemenS,oneofthestudents,surveysthenewlybuiltbeachdailyforsignsofnestingactivity.ThebeachsegmentchosenbyMarjorieandhercolleaguespartitionedthebeachintoalter-nating protected and unprotected 5 × 5 msquares.Anelectric fenceabout1mhighprotectstheexperimentalplotsonthebeach(Fig.39).Rigidpolesareplacedoneachcor-nerofaplotandonesupportpolebetweeneachcorner.Thelowestwireis10cmabovethegroundsonestingfemaleterrapinscanpassbelowwithouttouchingit.Walkingoreven crawling foxes and racoons will get

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Fig.35.ThetracksofSnappingturtlesshowdraggingmarksofthetail.Photo:B.Pfau.

Fig.34.TrackofaDiamondbackterrapin.Photo:B.Pfau.

anelectricshockwhentheytouchthewirewhentryingtogetintotheprotectedarea.Thetopwires,approximately1mabovethegroundpreventmammalsfromjumpingthefence.Thevoltageissimilartothatusedinhorsepasturesbecauseweakcurrentswillnotdeter adetermined racoon.Of course,signswarnhumansaboutthedangeroftheelectric fence colored flags clearly markcornersofthefencedsquares.

During thenesting season, the studentsinspectthebeachdailyfornestingactivity.Occasionally, snapping turtles, Chelydra serpentina, will wander onto the beachbut their tracks are easily distinguishedfromterrapins(Fig.34)bythelongtoenailmarksandthelargetaildrag(Fig.35).Attheendofthetrackfromtheriver,thenestcan be found where the female terrapin

hasconcealedthenestcavitywithturningmovements (Fig. 37). marJorie ClemenSgets the exact nest location using a hand-heldGeographicPositioningSystem(GPS)unit (Fig. 40). Normally the nest is leftundisturbed, but Willem digs up the nestto show us the eggs (Fig. 33). The eggsareabout10cmbelowsurface,fresheggsare translucent (Fig.38) and theybecomechalky white as they age. Of course, theeggswerereburiedafterwardsandthenestwasclosedcarefully.

Not all the turtle tracks lead to nests.Somefemalesreturnedtothewaterbecausetheyweredisturbedor theydidnot findafavourablenestingsite.Regrettably,Marjo-rieClemenSalsofindsdepredatedterrapinnests,butthesearenotintheareaprotectedbythefence(Fig.41).

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Fig.41.ThisunprotectednestofaSnap-pingturtlehasbeenraided.Onlyshrunkeneggshellsremain.Photo:B.Pfau.

Fig.39.Thewiresoftheelectricfencingarefastenedindifferentheightsabovetheground.Photo:B.Pfau.

Fig.38.Freshlylaidterrapineggsareso-mewhattranslucent.Photo:B.Pfau.

Fig.37.ThefemaleDiamondbackterrapinhascloseditsnestbyturningmovements.Photo:B.Pfau.

Fig.40.marJorieClemenStakesthegeo-graphicalcoordinatesofthenestusingaGPShandy.Photo:B.Pfau.

Fig. 36. The artificial nesting beach with youngplants.Photo:B.Pfau.

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marJorie’s project will demonstrate ifthefenceinfluencesnestingbehaviourandprotectsthenestsfrompredators.Thisisac-complishedbycomparingthenestnumbersand their survivorship between protectedand unprotected areas.The study has thepotentialtoresultinalowcostmechanismto protect nests in areas where nestingdensityandpredationratesarehigh.

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AuthorsDr.BeatePfauRathenaustraße1465326AarbergenGermanyE-Mail:[email protected]

WillemM.Roosenburg,AssociateProfessorDepartment of Biological Sciences Ohio University,Athens,Ohio45701USAE-Mail:[email protected]

Documents

Diamondback terrapins in Maryland: Research and conservation and Roosenburg 2010.pdfDiamondback terrapins (Malaclemys terrapin) appeal to humans because of their dark eyes, wide “smiling